Web cameras have been installed at all 96,000 polling stations with polling booth heads ordered to show every page of their electoral return to the cameras to guarantee transparency for the vote.

Voting in the Kamchatka and Magadan regions started at midnight Saturday/Sunday Moscow time. It will end after residents of Russia's westernmost Kaliningrad exclave vote at 9.00pm Moscow time Sunday.

Exit polls' results will be announced after voting is finished, and the first preliminary official results are expected to be made public by midnight Sunday/Monday or in the early hours Monday.

Putin, who was Russia's president between 2000 and 2008 and has been prime minister since then, has led the race. But he may be forced into a second round if he gets less than 50% of the vote in the first.

The winner in the first round will be inaugurated as president in early May and President Dmitry Medvedev, a junior member of the ruling tandem with Putin, will step down.